Insulator



R. H. WALKER INSULATOR Dec. 28, 1937.

Filed April 24, 1935 kn-MMW ATTORNEY Patented Dec. 28, 1937 UNITED STATES PATENT OFFICE INSULATOR Application April 24, 1935, Serial No. 17,981

1 Claim.

This invention relates to electric insulators and especially to insulators for use in regions where the atmosphere is apt to be contaminated with fog, dust, smoke or other foreign matter which is apt to collect upon the surface of the insulator and diminish its efficiency.

One object of the invention is to provide an insulator having a relatively short section length and having long fiashover and leakage paths, considerable portions of which are protected from contamination.

A further object of the invention is to provide an insulator having a minimum exposure of metal surfaces.

A further object of the invention is to provide an insulator having a rounded outer surface that will shed dust and other foreign matter.

A further object of the invention is to provide a device of the class named which shall be of improved construction and operation.

Other objects and advantages will appear from the following description.

The invention is exemplified by the combination and arrangement of parts shown in the accompanying drawing and described in the following specication, and it is more particularly pointed out in the appended claim.

In the drawing:

Fig. 1 is an elevation with parts in section showing one embodiment of the invention.

Fig. 2 is a fragmentary view showing a modiiication of a detail.

The insulator shown in Fig. 1 comprises two dielectric members I0 and I I which may be made of suitable insulating material, such as porcelain. The upper member III has a downwardly extending boss I2 having an upwardly opening recess in which a pin I3 is secured by cement I4. The upper end of the recess about the pin may be filled with asphalt or other suitable water-proofing material I5. The lower dielectric member II has an upwardly projecting boss I6 having a recess opening downwardly in which a pin II is secured by cement I8. The two bosses I2 and I6 are arranged end to end in axial alinement and are connected by a metallic sleeve I9 which may be provided with a web 20 separating the two portions of the sleeve to facilitate assembly of the bosses within the sleeve. The bosses are se- 50 cured in the sleeve by cement 2|. Each section of the sleeve is similar to the metal cap commonly used for suspension insulators except that instead of having an attaching member, the cover portions of the two caps are made in one so that a double cap is provided having oppositely directed openings for receiving the bosses of the respective dielectric members. This arrangement brings the two bosses close together and provides a closely coupled double insulator unit.

Each of the dielectric members In and II is provided with radially projected flanges, the anges of the upper member being curved downwardly to provide an outer petticoat 22 which overlaps an upwardly projecting ange or baiile 23 on the lower dielectric member. A supplemental skirt Z-l may be provided on the upper member so that the baffles 22, 23 and 24 cooperate to enclose the space aboutJ the sleeve I9 and form a labyrinthine passage connecting the interior of this space with the outer atmosphere. It will thus be seen that the surface of the two porcelain members adjacent the sleeve I9 is always protected from contamination and provides a clean, dry leakage path of considerable extent between the two terminals I3 and Il. The lower dielectric member I I may be provided with additional skirts 25 and 26 to further increase the leakage and flashover path of the insulator or the two skirts 25 and 2B, shown in Fig. 1, may be replaced by a single skirt 21 extending outwardly at an inclination, as shown in Fig. 2.

It will be seen that the invention provides an insulator unit of relatively short string length having double dielectric strength due to the two dielectric members; the overall length being but very little greater than that of the usual unit having a single dielectric member. In addition, the two dielectric members are provided with overlapping flanges which insure an extended surface protected at all times from contamination. The insulator is also provided with an extended smooth outer surface which will be kept washed by rain so as to further increase the efficiency of the unit. The upper metal iitting, instead of being an extended cap, is a pin of limited extent so that very little of the metallic surface is exposed.

I claim:

An insulator unit comprising a pair of dielectric members each having a boss thereon, a sleeve connecting said bosses to secure said dielectric members together, a radially extending flange on each of said dielectric members, skirts on said iianges directed inwardly toward each other and enclosing the space about said sleeve and forming a labyrinthine passage connecting said space with the surrounding atmosphere, said bosses having outwardly opening recesses therein, said recesses being closed at their inner ends by the material of said bosses, and attachment pins secured in said recesses for connecting said insulator unit to other units in a string, the inwardly directed position of the skirts providing clearance for close coupling of said units in the string so as to secure a minimum string length, while at the same time the skirts enclose the sleeves of the various units in the string producing a string having a minimum exposure of its fittings.

ROBERT H. WALKER. 

